Well Mega Pinsir's broken and likely to be suspected next, so it doesn't count
Mega Lucario and Charizard are miles more broken than Pinsir. Pinsir does one thing and can be prepared for. Lucario and Charizard get to pick and choose battles and are a complete gamble to counter without risking the sacrifice of at least one member. Both variants of both Pokemon are capable of dealing massive damage to even their own attacking stat's walls. Charizard Y's Fire Blast 3HKOs Blissey and 2HKOs Florges, while Lucario can run the gambit of specialized to mixed to take out anything not designed specifically to counter it and it alone.
Pinsir loses not just to one of the most used mons in the game, but also to anything designed as a general physical wall or tank without needing specific builds against it.
Checking since this was posted, Mega-Lucario was indeed banned. Charizard is much more suspect than Pinsir still. Aerialate QA is strong, and Air Return is formidable, but much, much more able to be dealt with than the gamble of Cherry, and still outclassed by bravestbird.swf.